The 737 Max has been the best-selling plane in Boeing’s history. However, after the two recent 737 Max 8 crashes – the Lion Air crash last October and the Ethiopian Airlines crash earlier this month – the global community has imposed a prohibition on the use of these planes (and in some cases 737 Max-variants).

To appreciate the psychology associated with these events, consider that in total, 346 people died on these two flights. That figure corresponds to the average number of automobile fatalities that occur in the U.S. in slightly more than three days. The average daily fatality rate on U.S. roads is about 110. Given the time between the two 737 Max 8 air crashes, the daily fatality rate from the two crashes is 2.6 per day. Moreover, in the 17 months or so since the 737 Max came into general service, there have been tens of thousands of flights of these planes, almost all without a major incident.

There is no global ban on motor vehicles, despite the much higher fatality rate for automobiles. To be sure, planes are more expensive than cars. However, this does not appear to explain why planes get banned but not cars, in response to crashes. We ban planes because psychologically, people dread being killed in plane crashes much more than they do being killed in car crashes. At issue is the psychological gap between perceived risk and actual risk. Research by psychologist Paul Slovic has shown that this gap is large for risks that people truly dread, as well as feel they do not understand well.

The most recent 737 Max incident has brought home the point that there is a lack of understanding of what truly caused the two planes to crash. Suspicion centers on the 737 Max’s Maneuvering Characteristics Augmentation System (MCAS), which takes control from the pilots and tilts the plane’s nose down in response to a sensor indicating the presence of a problem with the direction of the nose. This appears to have been the problem with the Lion Air crash.

In 2018, two pilots filed safety reports with the FAA, after the noses of their 737 Max planes suddenly tilted down when they engaged the autopilot. The autopilot is different from the MCAS, as the FAA noted, which of course reduces understanding of the associated risk.

Lack of knowledge, the fear of a loss of control by pilots, and the dread of being a passenger on a plane that is plunging to its demise: these combine to generate extremely high perceived risk.

Boeing’s management is hardly without blame in the 737 Max fiasco. There is strong documentation that for psychological reasons, people are reluctant to share information. Certainly, Boeing failed to share with airlines information that the MCAS can take control away from pilots when a sensor indicates that the plane’s nose direction is problematic.

Overconfidence is another well documented behavioral trait. Overconfidence leads people to underestimate risks. Typically, engineers mitigate overconfidence by building multiple backup systems, and avoiding single points of failure, wherever possible. In what can only be described as massive overconfidence, Boeing configured its software to allow a single sensor to activate the MCAS and take control away from pilots, even if the sensor reading is faulty. In other words, Boeing intentionally introduced a risk single point of failure into the 737 Max system.

Boeing promoted the 737 Max as being so similar to the older 737 models, that minimal pilot training was necessary to move from the older model to the new one. Certainly, overconfidence can lead people to underestimate risks.

At the same time, pressure to perform can lead people to knowingly take high risks. The latter phenomenon is called aspiration-based risk-seeking. Boeing developed the 737 Max as an ambitious response to strong competition from Airbus. High ambition in combination with a strong desire to succeed generates a high appetite for risk, and a susceptibility to taking imprudent risk. Certainly, insufficient pilot training adds to risk. The drive to succeed at Boeing was strong enough to generate a timeline in which the no training flight simulator was ready before the plane went into commercial use, despite pilots' expressed desire for appropriate training.

The 737 Max has certainly had an inauspicious beginning, as did Boeing’s Dreamliner. If the past is prologue, the kinks in the 737 Max will eventually get worked out. It is just that human psychology makes the process that much more expensive, both in dollars and in lives lost.